// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_PUBLIC_CHILD_V8_VALUE_CONVERTER_H_
#define CONTENT_PUBLIC_CHILD_V8_VALUE_CONVERTER_H_

#include <memory>

#include "base/callback.h"
#include "content/common/content_export.h"
#include "v8/include/v8.h"

namespace base {
class Value;
}

namespace content {

// Converts between v8::Value (JavaScript values in the v8 heap) and Chrome's
// values (from base/values.h). Lists and dictionaries are converted
// recursively.
//
// The JSON types (null, boolean, string, number, array, and object) as well as
// binary values are supported. For binary values, we convert to WebKit
// ArrayBuffers, and support converting from an ArrayBuffer or any of the
// ArrayBufferView subclasses (Uint8Array, etc.).
class CONTENT_EXPORT V8ValueConverter {
public:
    // Extends the default behaviour of V8ValueConverter.
    class CONTENT_EXPORT Strategy {
    public:
        typedef base::Callback<std::unique_ptr<base::Value>(v8::Local<v8::Value>,
            v8::Isolate* isolate)>
            FromV8ValueCallback;

        virtual ~Strategy() { }

        // If false is returned, V8ValueConverter proceeds with the default
        // behavior.
        // Use |callback| to convert any child values, as this will retain
        // the ValueConverter's internal checks for depth and cycles.
        virtual bool FromV8Object(v8::Local<v8::Object> value,
            std::unique_ptr<base::Value>* out,
            v8::Isolate* isolate,
            const FromV8ValueCallback& callback) const;

        // If false is returned, V8ValueConverter proceeds with the default
        // behavior.
        // Use |callback| to convert any child values, as this will retain
        // the ValueConverter's internal checks for depth and cycles.
        virtual bool FromV8Array(v8::Local<v8::Array> value,
            std::unique_ptr<base::Value>* out,
            v8::Isolate* isolate,
            const FromV8ValueCallback& callback) const;

        // If false is returned, V8ValueConverter proceeds with the default
        // behavior. v8::Object is passed as ArrayBuffer and ArrayBufferView
        // classes are siblings.
        virtual bool FromV8ArrayBuffer(v8::Local<v8::Object> value,
            std::unique_ptr<base::Value>* out,
            v8::Isolate* isolate) const;

        // If false is returned, V8ValueConverter proceeds with the default
        // behavior. This allows to intercept "non-finite" values and do something
        // with them.
        virtual bool FromV8Number(v8::Local<v8::Number> value,
            std::unique_ptr<base::Value>* out) const;

        // If false is returned, V8ValueConverter proceeds with the default
        // behavior.
        virtual bool FromV8Undefined(std::unique_ptr<base::Value>* out) const;
    };

    static V8ValueConverter* create();

    virtual ~V8ValueConverter() { }

    // If true, Date objects are converted into DoubleValues with the number of
    // seconds since Unix epoch.
    //
    // Otherwise they are converted into DictionaryValues with whatever additional
    // properties has been set on them.
    virtual void SetDateAllowed(bool val) = 0;

    // If true, RegExp objects are converted into StringValues with the regular
    // expression between / and /, for example "/ab?c/".
    //
    // Otherwise they are converted into DictionaryValues with whatever additional
    // properties has been set on them.
    virtual void SetRegExpAllowed(bool val) = 0;

    // If true, Function objects are converted into DictionaryValues with whatever
    // additional properties has been set on them.
    //
    // Otherwise they are treated as unsupported, see FromV8Value.
    virtual void SetFunctionAllowed(bool val) = 0;

    // If true, null values are stripped from objects. This is often useful when
    // converting arguments to extension APIs.
    virtual void SetStripNullFromObjects(bool val) = 0;

    // Extend default behavior of V8ValueConverter.
    virtual void SetStrategy(Strategy* strategy) = 0;

    // Converts a base::Value to a v8::Value.
    //
    // Unsupported types are replaced with null.  If an array or object throws
    // while setting a value, that property or item is skipped, leaving a hole in
    // the case of arrays.
    // TODO(dcheng): This should just take a const reference.
    virtual v8::Local<v8::Value> ToV8Value(
        const base::Value* value,
        v8::Local<v8::Context> context) const = 0;

    // Converts a v8::Value to base::Value.
    //
    // Unsupported types (unless explicitly configured) are not converted, so
    // this method may return NULL -- the exception is when converting arrays,
    // where unsupported types are converted to Value(Type::NONE).
    //
    // Likewise, if an object throws while converting a property it will not be
    // converted, whereas if an array throws while converting an item it will be
    // converted to Value(Type::NONE).
    virtual std::unique_ptr<base::Value> FromV8Value(
        v8::Local<v8::Value> value,
        v8::Local<v8::Context> context) const = 0;
};

} // namespace content

#endif // CONTENT_PUBLIC_CHILD_V8_VALUE_CONVERTER_H_
